My HRM is a LIAR!

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jchun5
jchun5 Posts: 3
in Health and Weight Loss
Not exactly a liar... but I'm having a hard time trusting the calories burned after my exercise. I'm 6'2 and 192 lbs. I do a brisk walk about 3.7 mph around a fitness trail (with lots of inclines) that is 4.7 miles in distance and it takes me on average 1 hour and 12-15 minutes. My HRM (Polar FT7) always tells me I burned anywhere between 650-750 calories. However, after doing some research on walking and calorie burn I should be burning around 110 cal/mile which comes out to only 517 calories ... more than a 100 calorie difference ... (significant?)

I use my HRM data for my MFP exercise diary and I keep overclocking my calorie deficit and I'm afraid to eat more if the HRM data is feeding me LIES!

any advice....?

Replies

  • SherryTeach
    SherryTeach Posts: 2,836 Member
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    It sounds about right to me. My HRM tells me that I burn around 200 calories in 40 minutes on the treadmill at 3.5 mph. And I'm 5'1" and 104 pounds.
  • albayin
    albayin Posts: 2,524 Member
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    it might be a bit higher...considering the known number is about 80 cal/mile walking, running might burn a tab more per mile..but not much more...if you are bigger then around 100 cal/mile might be a safe reference point? I don't know for sure....
  • albayin
    albayin Posts: 2,524 Member
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    if you have input everything about yourself correctly, how high does your heart rate get?
  • WalkingAlong
    WalkingAlong Posts: 4,926 Member
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    I'd trust the HRM over the formula because the formula must not know anything about the inclines. 750 for under 5 miles sounds hefty but I don't know anything about the inclines so it could be realistic. 10 calories a minute for walking-- you've got to be really huffing. Check out the chart at the end of this article for some sample calorie burns in that range.

    http://www.mayoclinic.org/healthy-living/weight-loss/in-depth/exercise/art-20050999
  • jchun5
    jchun5 Posts: 3
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    i think my heart rate was going in between 150-160. I think it was kinda high because it was around 95 degrees outside and super humid. Normally when I jog my HR is around 130-140...
  • jchun5
    jchun5 Posts: 3
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    Thanks everyone for replying to my post!
  • 3dogsrunning
    3dogsrunning Posts: 27,167 Member
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    The accuracy of HRMs tend to be vastly overstated here. Here are a couple of posts that may help you

    http://www.myfitnesspal.com/blog/Azdak/view/the-real-facts-about-hrms-and-calories-what-you-need-to-know-before-purchasing-an-hrm-or-using-one-21472

    http://www.myfitnesspal.com/topics/show/774337-how-to-test-hrm-for-how-accurate-calorie-burn-is

    and this one (it is included in the one above)

    http://www.myfitnesspal.com/topics/show/773451-is-my-hrm-giving-me-incorrect-calorie-burn
  • CallMeCupcakeDammit
    CallMeCupcakeDammit Posts: 9,377 Member
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    Did your research include walking at an incline? Because that's going to obviously raise your heart rate more than a flat trail.
  • Bj0223
    Bj0223 Posts: 133 Member
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    If I exercise more than an hour I deduct 100-125 calories from the HRM total. I figure I would have burned that amount doing nothing at home or staying in bed. I record what I think is above my usual calorie burn. So if you do that your HRM would be right on target.
  • ravenmiss
    ravenmiss Posts: 384 Member
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    I've only ever used my HRM for Zumba, my heart is usually above 170 and can hit 185+ and I usually average ~10cals a minute according to mine, I'm 5ft6/f/230lb so for a 70min Zumba session it will give around 650-700 but for the purposes of error etc I usually log around 500 and it's never halted my weightloss.

    ETA: Mine is a Polar FT4 all set up correctly.
  • SLLRunner
    SLLRunner Posts: 12,942 Member
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    I ran four miles in 38 minutes this morning and my FT7 HRM said i burned about 400 calories, and I'm 5 ft 4.5 and 139 pounds AND 52.

    Why do you think your HRM is inaccurate?
  • ekat120
    ekat120 Posts: 407 Member
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    I use this formula:

    http://www.runnersworld.com/weight-loss/how-many-calories-are-you-really-burning?page=single

    It distinguishes between net and gross calories, and based on my logging at least, it seems pretty accurate.
  • thenk83
    thenk83 Posts: 22 Member
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    Usually MFP and my HRM aren't too far apart when I run. My HRM is usually 20-40 calories under what MFP states. That's weird you have such a big gap. Does your HRM have the latest firmware and such?

    This might help....
    http://www.runnersworld.com/tools/calories-burned-calculator
  • SLLRunner
    SLLRunner Posts: 12,942 Member
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    Usually MFP and my HRM aren't too far apart when I run. My HRM is usually 20-40 calories under what MFP states. That's weird you have such a big gap. Does your HRM have the latest firmware and such?

    This might help....
    http://www.runnersworld.com/tools/calories-burned-calculator
    My heart rate monitor is always at least 100 calories, if not more, less than MFP and any internet resource. It has been at least 200 calories less than the treadmill.
  • tycho_mx
    tycho_mx Posts: 426 Member
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    Conveniently, calorie estimates are very reliable for "on foot" exercises. They basically don't depend on speed - only mass (weight) and distance matter.

    So you cover 3 miles and weight 200 lb? Use a calculator, not your HRM. Too much variability, opaque algorithms (some include basal burn! So even if you're sleeping you're burning. Which is true, but then you don't add that to your caloric expenditure!). If you are actually running outside and know the profile (your phone's GPS can give you an idea of the altitude gain) I'd rather use an online calculator.

    http://www.runnersworld.com/tools/calories-burned-calculator (flatland)
    http://www.nwhiker.com/calorieburn.html (with altitude)

    My HR goes up whenever I see a cute runner going past - doesn't mean I'm working out harder :) It also goes up if it is hot, and goes down if I've been training too hard. It's a bit unreliable (for some workouts, that's the best you get, though).

    So - to take home. HR has a lot of variability. 2. Calories while running/walking depend really only on distance and body weight, since the speed is so low air resistance is negligible (unless you're running in a gale?)

    EDIT : If i remember correctly, this didn't apply to treadmills. Those burn less than the estimate unless set past a given slope due to other mechanics at play. And yeah, I know it sucks that a HRM is not trustworthy (I own one and use it every day, but not for calorie estimates anymore). If you want the journal articles for the correlation between running distance and mass (and not speed) and promise to read them I'll fish them out.
  • aliakynes
    aliakynes Posts: 352 Member
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    I recommend a walking calculator rather than a running one (as suggested above). There is a difference.
    http://walking.about.com/library/cal/uccalc1.htm -- this one puts you at between 479 and 513 calories (3mph vs. 4 mph)

    Of course that's without the incline. If you can find out what the elevation is, you can look up a hiking calculator. That will probably be more accurate.
  • albayin
    albayin Posts: 2,524 Member
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    Usually MFP and my HRM aren't too far apart when I run. My HRM is usually 20-40 calories under what MFP states. That's weird you have such a big gap. Does your HRM have the latest firmware and such?

    This might help....
    http://www.runnersworld.com/tools/calories-burned-calculator
    My heart rate monitor is always at least 100 calories, if not more, less than MFP and any internet resource. It has been at least 200 calories less than the treadmill.

    this^^ My hrm gives me 450 after a five mile run out side at 10 pace but MPF gives almost 600 burn...

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